How to create line chart in Flutter

Key takeaways:

• Line charts are a fundamental tool in mobile app development for visualizing data trends over time or ordered categories. Using Flutter's fl_chart library simplifies the creation of interactive line charts.

• To use fl_chart, add the package in the pubspec.yaml file under the dependencies section, and install it by running flutter pub get or using the terminal command.

• The LineChart widget in Flutter uses LineChartData for its configuration. Essential components include FlBorderData (to control chart borders) and LineChartBarData (to define lines and their respective data points with FlSpot objects).

• By incorporating the LineChart widget into your Flutter widget tree and defining its data, you can display a customized line chart. The entire implementation process is streamlined and can be enhanced with detailed settings for aesthetics and interactivity.

What is a line chart?

Line charts are an essential visualization tool in mobile app development. They clearly represent data trends over time or ordered categories. Flutter, a popular cross-platform UI toolkit, offers a straightforward way to create interactive line charts.

Creating a line chart in Flutter

In this Answer, we'll learn how to create a line chart in Flutter using the fl_chart library. We'll walk through the steps, from setting up the project to writing the necessary code to display a simple line chart with data points.

Step 1: Adding dependency

To begin using line charts, we must install the necessary package. For this purpose, we will open the pubspec.yaml in our Dart project and add the following line under the dependencies section:

After making the changes, we can install the package in two ways:

• Right-click the pubspec.yaml file and click “get packages."

• Write the following command in the terminal.

We can skip all the above steps and just run the following command, which will automatically install the latest version of the fl_chart package.

Step 2: Adding import package statement

Now, we can import the package into the Dart file by adding the following line of code in the Dart file where we want to implement the fl_chart function:

Step 3: Define the data for the line chart

Let’s assume we have some sample data representing points on the line chart for demonstration purposes. We’ll create a simple list of data points (x, y) pairs:

Step 4: Create the LineChart widget

In our Flutter widget tree, we will now create a new LineChart widget to display the line chart:

• Lines 7–17: Inside Container, we use the LineChart widget to create the line chart. The LineChart widget takes a LineChartData object as its data.

  • Lines 12–15: The LineChartData object contains the configuration data for the line chart, such as border settings, line bars data, etc. In this case, we set borderData to FlBorderData(show: false), which means we hide the border around the chart.

    • Line 13: We define a list of LineChartBarData objects inside lineBarsData. Each LineChartBarData object represents a single line on the chart.

    • Line 14: Inside each LineChartBarData, we define a list of FlSpot objects in the spots property. Each FlSpot represents a data point on the line chart with x and y coordinates.

Complete code

We get the following output by putting together the code explained above.

Conclusion

Creating line charts in Flutter using the fl_chart library is a powerful way to visualize data trends and patterns. With just a few simple steps, we can integrate line charts into our Flutter apps, enabling users to grasp important insights at a glance. We can further enhance the chart’s appearance and interactivity by exploring the various configuration options provided by the fl_chart library.